US3134527A

US3134527A - Tape driving means

Info

Publication number: US3134527A
Application number: US163804A
Authority: US
Inventors: Jack K Willis
Original assignee: Ampex Corp
Current assignee: Ampex Corp
Priority date: 1962-01-02
Filing date: 1962-01-02
Publication date: 1964-05-26
Anticipated expiration: 1981-05-26
Also published as: DE1424497A1; GB987721A

Description

May 26, 1964 J. K. WILLIS TAPE DRIVING MEANS 5 Sheets-Sheet l Filed Jan. 2, 1962 In .ll-MHIH L/ACK /K l/l//L L /5 INVENToR. By wg@ A from/Ey May 26, 1964 .1. K. WILLIS TAPE DRIVING MEANS 5 Sheets-Sheet 2 Filed Jan. 2

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TTOP/VEY May 26, 1964 J. K. WILLIS TAPE: umn/ING MEANS 5 Sheets-Sheet 3 Filed Jan. 2

JACK K W/L ./.v/S INVENTOR BY M195/ 6,?

May 26, 1954 J. K. WILLIS 3,134,527

TAPE DRIVING MEANS Filed Jan. 2, 1962 5 Sheets-Sheet 4 c/ACK K l/i//LL/S IN VEN TOR.

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May 26, 1964 J. K. WILLIS TAPE DRIVING MEANS 5 Sheets-Shee. 5

Filed Jan. 2, 1962 c/ACK /C #10M/.5`

INVENTOR.

United States .Patent O 3,134,527 TAPE DRIVING MEANS Jack K. Willis, San Bruno, Calif., assignor to Ampex Corporation, Redwood City, Calif., a corporation of California Filed Jan. 2, 1962, Ser. No. 163,804 8 Claims. (Cl. 226-97) This invention relates to tape driving means, and particularly to apparatus employing fluid or air pressure differentials to move the tape.

In the magnetic tape recorder art, it has been proposed to eiect initial threading of a tape through a tube or channel leading from a supply reel past the transducing heads and to a take-up reel, the tape being moved by means of an air pressure differential applied to the leading end of the tape. Such an operation has been demonstated to be feasible; however, delay and wear of the tape sometimes occurs because the tape has a tendency to move from side to side in the channel, dragging, flapping and beating against the walls.

In another application, air pressure differentials have been used in association with capstan means to provide metering of the tape after threading and during recording and reproduction. Such arrangements require a constant speed motor just as do ordinary capstans and the procedure of threading the tape past the capstan is intricate and time consuming.

Accordingly, it is an object of the present invention to provide uid or air pressure operated means to drive a tape Without the use of a capstan or capstan motor, and particularly to drive the leading end of the tape from a supply to a take-up reel for the threading of the tape thereon.

It is another object of the invention to provide an air pressure operated means for threading a tape without delay of or damage to the tape.

It is a further object of the invention to provide a pneumatic tape driving means capable of starting, threading, driving, stopping and reversing a tape without sticking, binding, dragging, wearing or destruction or the tape.

These and other objects are attained in a structure in which an enclosed channel is provided from the supply to the takeup reel and the tape is driven therethrough by means of dilerential air pressure directed at a suitable driving angle against one side only of the tape, the other side of the tape being fn'ctionlessly but solidly supported to prevent flapping motion. A portion of the channel is arranged to collapse when the air pressure differential is removed, so as to brake and stop the tape. For reverse movement, the driving air is directed at a suitable reverse driving angle.

Further objects and advantages together with a better understanding of the invention may be had by reference to the following description, taken in conjunction with the accompanying drawing, in which:

FIGURE 1 is a broken-away front elevation view of a tape transport constructed in accordance with the invention, and illustrating the threading mode of operation;

FIGURE 2 is a view similar to that of FIGURE l and illustrating the forward recording and reproducing modes of operation;

FIGURE 3 is a view similar to that of FIGURE 1 and illustrating the stopping of the tape;

FIGURE 4 is a view similar to that of FIGURE 1 and illustrating the reverse mode of operation;

FIGURE 5 is a broken-away perspective view, to an enlarged scale, of a portion of the apparatus shown in FIGURE 1; and

FIGURE 6 is a broken-away perspective view, to an enlarged scale, of another portion of the apparatus shown in FIGURE 1.

Patented May 26, 1964 ICC Referring now to FIGURE 1, there is shown a tape transport 11 including a supply reel 12 and a take-up reel 13 operated by a pair of respective motors 14 (FIGURE 6). The reels 12--13 are enclosed in a unitary housing 16 that defines a channel 17 for the passage of a magnetic tape 18 from the supply reel 12 to the take-up reel 13. Along the path of the tape 18 and midway between the reels, there are positioned a plurality of magnetic transducing

heads

21, 22, 23 and 24.

To provide an air pressure diiferential for use in threading and transporting the tape 18, a differential pressure source 26 is provided. The source 26 has a relatively high pressure side 27 and a relatively low pressure side 28, and may be constructed in any of a number of ways well known in the art. For example, the source 26 may be a suction pump having a suction inlet corresponding to the low pressure side 28 and a high pressure air outlet corresponding to the high pressure side 27. Alternatively the source 26 may be a suction pump having only a low pressure side 28, the high pressure side being open to the ambient atmosphere; or it may be arranged so that the high pressure side 27 is coupled to the systen and the low pressure side 28 is open to the ambient atmosphere. In any of these arrangements however it will be seen that the source 26 establishes an air pressure differential between two pressure values one of which may or maynot be ambient atmospheric pressure. n When it is desired to assemble the supply reel 12 together with the tape 18 wound thereon in the transport 11 for the purpose of recording or playing the tape, a pair of

doors

31 and 32 are opened in the housing 16, and the supply reel 12 is mounted on a keyed spindle (not shown). The doors 31-32 are then closed and latched as by means of a latch 34 so that the housing 16 forms a closed system in which the air pressure diiierential may be eiectively controlled. The motors 14 are then started in a forward or clockwise direction as shown by the arrows 36 and 37; and the source 26 is connected to the housing 16 in such a way as to establish an air pressure differential gradient decreasing from the supply reel 12 and through the channel 17 to the take-up reel 13. The tape 18 coming from the revolving supply reel 12 is then drawn by the ow of air past the transducing heads 21-24 to the take-up reel. Y

The necessary ow of air is established by coupling the high pressure side 27 of the source 26 to a number of

air input elements

41, 42, 43, 44, 45, 46 and 47 forming an interior lining for the housing 16` and in effect dening the channel 17; and by connecting the low pressure side 28 of the source 26 to the hub 48 of the take-up reel 13.

As shown'in FIGURE 1, the

elements

41, 42, 45, 46

Vand 47 are made of relatively thick portions of a porous tape in forward motion. Thus the air is predisposed to flow from left to right and to drive the tape in such a direction. -The porous element 47 forming the lower wall of the channel 17 is particularly arranged to provide anti-friction support and flotation of the tape under the strong driving forces of the air from openings 49. The

elements

41, 42, 45, 46 and 47 are supplied as by means of

respective supply chambers

51, 52, 55, 56 and 57 dened by the corresponding porous elements and the Aexterior wall of the housing 16. These chambers'Sl, 52,

55, 56 and 57 communicate with the high pressure side 27 of source 26 as by means of

respective conduits

61, 62, 65, 66 and 67.

It is here noted that a typical characteristic of the porous material is to provide a pressure drop of the air owing therethrough so that the air coming out into the channel 17 is at a substantially lower pressure than the air coming from the source 26. Consequently the air coming tothe channel 17 from the various porous members tends to form a low pressure, evenlyA distributed .lubricating pad of air, indicated bythe small arrows 71,

and functioning to keep the tape from encountering and sticking against the upper and lower walls ofthe channel 17 during passage to the take-up reel 13. The main tape driving force represented by the directional air ow is supplied by a combination of the

elements

43 and 44 and the low pressure outlet from the hub 48 of the take-up reel 13; and the structure of these elements is described as Y e follows:

76 directed downwardly and toward the left through the* lower` wall 73. The housing 72 also defines a pair of longitudinal chambers 77 and 78 above the chambers 74-75. The chamber 77 communicates with each of the chambers 74 by means of openings 81 formed in the dividing wall, and the chamber 78 communicates with each of the chambers 75 by means of openings 82. 'A flexible conduit 83 couples the chamber 77 to a valve 86 (FIGURE l), and a ilexible conduit 84 couples the chamber 78 tothe valve 86. vAs illustrated in FIGURE l the valve 86-is actuated during threading in the forward drive mode of operation so as to effecta direct coupling from the high pressure side 27 of the source 26, through.

conduit 83 and the Vchambers 77 and 74, and to the angled openings 49; while at the same time the conduit 84 and corresponding reverse angle drive openings 76 are blockedV bythe valve 86 from communication with the source 26. The element 43 is pivoted as by means of a pivot pin 91 solidly mounted in the housing 16 midway of the array Ypresses it securely againstthe element 47 defining the lower portion of the channel 17 The element 44 as shown in thedrawing is an exact duplicate of theelement 43 andis pivoted on the same pivot'pin 91 but faces in an i opposite direction. A spring element 93 is mounted on the pin 91 and bears against both of the

elements

43 and 44 so as to urge them toward the element 47 even if the transportv should be inverted.` However, as shown in FIGURE l, when air under pressure is forced yfrom the Tsource 26 through the angled openings 49, the pressure of the'emitted air forces the

elements

43 and 44 to pivot upwardly and to leave a space beneath for the passage of the tape 1S. When the valve 86 is reversed as shown in FIGURE 4 for reverse operation a similar effect obtains,

91'in such a way as to clear the transducing heads 21-24 Veven in the stopped or braking position.

Referring now to FIGURE 6, the construction of the take-up reel 13 to receive and hold thetape 18`is shown. The hub `4S of the reel is formed as a hollow cylinder aixed to and supported on a central shaft 101, the latter being coupled to or formed as extension of the output shaft of motor 14. The hub cylinder 48 has formedin the outer cylindrical wall a number of axially aligned slits 102 arranged to be encountered by the tape 18. A pair of reel side flanges 103 are mounted on the hub on either side of the zone of the slits 102. Spaced laxially from the zone of slits 102 is another array of slits 104 similarly arranged in the hub cylinder 48; and surrounding and enclosing the zone of slits 104 is a manifold member 106, this member being solidly mounted on the housing 16 and being provided with a conduit 107 leading therefrom to the low pressure side 28 of the source 26. During the lirst part of the threading operation, the source 26 draws air by suction from'the channel 17, through the slits 102 in the rotating hub' 48 andintothe interior of the hub, thence outwardly through the slits 104 and into the manifold 106, and thence through the conduit -107 to the source 26. Because all of the air in the channel 17 passes out eventually through the slits 102, the leading end of the tape 18 is drawn to the hub and becomes rmly kand flatly clamped thereto in such a way as to `cover the slits 102. A set offoutletopenings 110 may be .provided in the end ofv cylinder 48 yto permit escape of air after the threading operation has been completed.

A pair of slack

loop tape columns

111 and 112 are provided communicating with the interior of housing 16 directly over the axes of

respective reels

12 and 13 and between respective porous elements 41-42 and 45-46. YThe upper ends of thecolumns 111-112 have suction openings 113 and k114 respectively, coupled as by means of a pair of

conduits

116 and 117 to a valve 118, which in turn is coupled to the low pressure side 28 of source 26. In the threading mode of operation as shown in FIGURE l, the valve 118 is closed, so'that no air isiremoved from the channel 17 through the columns 111-- 112, and so that the tape is directed during the threading process from the reel 12 toward the reel 13. However after the tape has been successfullythreaded and ordinarily forward recording or playback of the tape is Y tained substantially at a desired medium length. It will be noted also in reference to FIGURE 2 that the porous ,elements 41--42 both project slightly beyond the mouth of the tape column 111 and are rounded so that guiding of the tape in the loop`121 is accomplished with minimum frictional engagement of the tape on the walls of the columns 111. As the tape enters and leaves the column 111, it oats frictionlessly on the cushion of low pressure air emanating from the rounded ends of elements 41-42. The elements 45-46 are similarly constructed at the mouth of tape column 112.

When it is desired to quickly stop the tape at the transducing heads 21-24, the valve 86 is turned to the neutral position as shown in FIGURE 3 with the result that the tape driving elements 43-44 lose their air pressure and spring toward the lower portion of the tape channel 17, pinching the tape and clamping it rmly thereto. Because the massive tape loaded

reels

12 and 13 cannot be stopped so quickly as the'comparatvely weightless segment of tape at the transducing heads, the tape loop 121V temporarily grows longer and the tape loop 122 temporarily grows shorter. When the reels12-13 have been'stopped however, they may beV rotated in a reverse direction to reestablish the tape loops y121-122 in the desired lengths,

or re-establishment of the tape loops may be Ypostponed until the apparatus is started again. 4

If, after stopping, Va reverse movement'of the tape is desired, the valve 86 is turned to the position illustrated in FIGURE 4,*and the reel motors 14 are energizedto drive the reels 14 in a counter clockwise direction asr in-l 'dicated'by the arrows 126 and 127. The high pressure 'air coming from the source 26 llows through the valve and conduit 84 to the angled openings 76 of tape driving elements 43-44. The air pressure from the openings 76 causes the elements to pivot away from the tape 18 and to drive the tape to the left toward the reel 12. Because the tape in the vicinity of the heads 21-24 can be thus started much more quickly than the

massive reels

12 and 13, the tape loop 121 temporarily grows longer While the loop 122 temporarily grows shorter. after the reel motors 14 have brought the reels to a speed slightly greater than the speed of movement of the tape 18, the loops 121-122 are re-established at medium lengths of the

reels

12 and 13 are slowed to correct operating speed.

It will be seen that during the driving of the tape by the tape driving elements 43-44 inthe threading and normal operating modes, the combined effect of the angled openings 49 (76) on the one side of the tape and the air owing from the porous member 47 on the other side of the tape is to smoothly drive the tape in the desired direction While firmly and frictionlessly supporting the tape against flapping, sticking and beating engagement with the sides of channel 17. This eect has been found to be realized in practice, essentially because the high pressure driving air is applied to the tape entirely on one side while the low pressure evenly distributed porous air on the other side serves to solidly support the moving tape. It has been found that the pressure of the air at the surface of porous member 47 is not substantially altered even if the tape approaches engagement with the porous member and effectively stops up the air flow from the porous cavities nearest the surface of the member. Thus transient pressure changes at the surface of the porous member are damped out and effectively avoided, with the result that flapping wave motion of the tape near the porous member is also effectively avoided.

Instead of forming member 47 of porous material and coupling the member to the air pressure source 26 the member 47 may be made entirely of solid antifriction material, such as for example, Teon. Thus, the effect of substantially frictionlessly supporting the tape on one side While driving it with a directed flow of air applied to the other side is still obtained.

Thus, there has been described a tape transport in which an enclosed channel is provided from the supply to the takeup reel and tape is driven therethrough by means of dilferential air pressure directed at a suitable driving angle against one side only of the tape, the other side of the tape being frictionlessly but solidly supported to prevent apping motion. The driving air is directed from a pair of pivotable tape driving members held in a retracted position during the driving mode by the pressure of the air emanating therefrom and arranged to pivotably collapse when the air pressure is removed so as to clamp the tape against the supporting member and effectively brake the tape to a stop. For reverse movement of the tape, the pressurized air is directed from the tape driving members at a suitable reverse drive angle.

What is claimed is:

1. Apparatus for driving a tape in a longitudinal direction, said tape having a predetermined thickness, comprising:

means for directing a flow of uid against one side of said tape an din said longitudinal direction for driving said tape; and

antifriction means on the opposite side of said tape for providing support for said tape at points spaced in said longitudinal direction for a dimension lying in the range from zero to the order of said tape thickness, said points of support also being distributed across the width of said tape,

whereby said tape is supported Without flapping during the longitudinal driving thereof.

2. Apparatus for driving a tape in a longitudinal di- However,

rection, said tape having a predetermined thickness, comprising:

means for directing a ow of fluid against one side of said tape and in said longitudinal direction for driving said tape; and

means for substantially frictionlessly supporting the lopposite side of said tape at points spaced in said longitudinal direction fora dimension lying in the range from zero to the order of said tape thickness, said points of support also being distributed across the width of said tape, i

whereby said tape is guided without flapping during the longitudinal driving thereof.

3. Apparatus for driving a tape in a longitudinal direction, said tape having a predetermined thickness, comprising:

a driving member confronting one side of said tape, said member being provided with a number of nozzle openings directed against said side of said tape and in said longitudinal direction for driving said tape;

means for directing a flow of fluid through said nozzle openings and against said tape; and

means for substantially frictionlessly supporting the opposite side of said tape at points spaced in said longitudinal direction for a dimension lying in the range from zero to the order of said tape thickness, said points of support also being distributed across the width of said tape,

4. Apparatus for driving a tape in a longitudinal direction, said tape having a predetermined thickness, comprising:

means for directing a first flow of uid against one side of said tape and in said longitudinal direction for driving said tape;

a guide member confronting said means on the opposite side of said tape; and

means for directing a second flow of fluid to the surface of said guide member confronting said tape at points spaced in said longitudinal direction for a dimension lying in the range from zero to the order of said tape thickness, said points of support also being distributed across the width of said tape,

5. Apparatus for driving a tape in a longitudinal direction, said tape having a predetermined thickness, comprising:

means for directing a iirst flow of fluid against one side of said tape and in said longitudinal direction for driving said tape;

a guide member formed of porous material confronting said means on the opposite side of said tape, said member having pores opening toward said tape across the width thereof and spaced in said longitudinal direction for a dimension lying in the range of from the order of to substantially less than said tape thickness; and means for providing a second flow `of fluid through said porous guide member and against said opposite side of said tape,

6.. Apparatus for driving a tape in a longitudinal direct1on, comprising:

anti-friction means for providing substantially unvarying supporting pressure on one side of said tape;

means for selectively directing a ow of uid against the opposite side of said tape and in said longitudinal direction for driving said tape, said second-named means being mounted for relative movement toward and away from said rst-named means; and

means for urging said second-named means toward said first-named means,

whereby said second-named means is forced away from said first-named means and said tape is driven in said longitudinal direction when said uid is owing -through said second-namedy means, but is clamped between said rstand second-named means when said uid ow is decreased.

7. Apparatus for driving a tape in a longitudinal direction, comprising:

'means for urging said second-named means toward said guide mmeber, v

Y whereby said second-named means is forced away from said guide member and said tape is supported Witho'ut flapping and is driven in said longitudinal direction when said fluid is owing through said secondnamed means, but is clamped between said secondnamed means and guide member when said fluid ow is decreased. f 8. Apparatus for threading and driving tape in a longitudinal direction, comprising:

a iirstrmember formed of porous material and confronting one side of said tape;

second and third members spaced apart and extending from said first member around opposite edges of said tape and dening with said first member a threading and driving channel for said tape;

a fourth member mounted between'said second and third membersjfor movement between positions releasing and clamping said tape against said rst member, said fourth member being spring loaded toward said clamping position, said fourth member also being provided with a plurality of nozzle openings directed at said tape and in said longitudinal direction;

means for directing a iirst flow of air inwardly through said first porous member for the stable flotation of said tape; and i means for selectively directing a second flow of air inwardly through said nozzle openings of said fourth member and against said tape,

whereby said fourth member is caused to move to said tape releasing position and said tape is driven longitudinally in said channel without apping when said second flow is flowing, but returns to said clamping position when said second flow is stopped.

References Cited in the file of this patent UNITEDv STATES PATENTS Great Britain Jan. 11, i961

Claims

1. APPARATUS FOR DRIVING A TAPE IN A LONGITUDINAL DIRECTION, SAID TAPE HAVING A PREDETERMINED THICKNESS, COMPRISING: MEANS FOR DIRECTING A FLOW OF FLUID AGAINST ONE SIDE OF SAID TAPE AND IN SAID LONGITUDINAL DIRECTION FOR DRIVING SAID TAPE; AND ANTIFRICTION MEANS ON THE OPPOSITE SIDE OF SAID TAPE FOR PROVIDING SUPPORT FOR SAID TAPE AT POINTS SPACED IN SAID LONGITUDINAL DIRECTION FOR A DIMENSION LYING IN THE RANGE FROM ZERO TO THE ORDER OF SAID TAPE THICKNESS, SAID POINTS OF SUPPORT ALSO BEING DISTRIBUTED ACROSS THE WIDTH OF SAID TAPE, WHEREBY SAID TAPE IS SUPPORTED WITHOUT FLAPPING DURING THE LONGITUDINAL DRIVING THEREOF.